Sitagliptin, (3R)-3-amino-1-[9-(trifluoromethyl)-1,4,7,8-tetrazabicyclo-[4.3.0]nona-6,8-dien-4-yl]-4-(2,4,5-trifluorophenyl)butan-1-one, has the following chemical structure:

Sitagliptin phosphate is a glucagon-like peptide 1 metabolism modulator, hypoglycemic agent, and dipeptidyl peptidase IV inhibitor. Sitagliptin is currently marketed in the United States as its phosphate salt in its monohydrate form under the trade name JANUVIA™. JANUVIA™ is indicated to improve glycemic control in patients with type 2 diabetes mellitus.
The following PCT Publications describe the synthesis of Sitagliptin via stereoselective reduction: WO 2004/087650, WO 2004/085661, and WO 2004/085378.
Several crystalline forms of Sitagliptin phosphate are described in the literature. WO 2005/020920 describes crystalline forms I, II, III, and an ethanol solvate; WO 2005/030127 describes crystalline form IV; WO 2005/003135 describes a monohydrate form; and WO 2006/033848 described the amorphous form.
Crystalline forms of certain Sitagliptin salts are described in PCT publications nos. WO 2009/085990, WO 2010/000469, and WO 2010/012781.
Polymorphism, the occurrence of different crystal forms, is a property of some molecules and molecular complexes. A single molecule may give rise to a variety of polymorphs having distinct crystal structures and physical properties like melting point, thermal behaviors (e.g., measured by thermogravimetric analysis—“TGA”, or differential scanning calorimetry—“DSC”), x-ray diffraction pattern, infrared absorption fingerprint, and solid state NMR spectrum. One or more of these techniques may be used to distinguish different polymorphic forms of a compound.
Discovering new polymorphic forms and solvates of a pharmaceutical product can provide materials having desirable processing properties, such as ease of handling, ease of processing, storage stability, and ease of purification or as desirable intermediate crystal forms that facilitate conversion to other polymorphic forms. New polymorphic forms and solvates of a pharmaceutically useful compound or salts thereof can also provide an opportunity to improve the performance characteristics of a pharmaceutical product. It enlarges the repertoire of materials that a formulation scientist has available for formulation optimization, for example by providing a product with different properties, e.g., better processing or handling characteristics, improved dissolution profile, or improved shelf-life. For at least these reasons, there is a need for additional polymorphs of Sitagliptin (or a salt thereof).
The present invention discloses solid state forms of Sitagliptin salts.